Parts of a Butterfly Valve: Detailed Guide and Functions

Introduction to Butterfly Valve Components

A butterfly valve is a versatile and widely used valve type in various industries, known for its compact design and reliable operation. Understanding its parts is essential for installation, maintenance, and troubleshooting. Each component plays a crucial role in controlling fluid flow efficiently.

Valve Body

The valve body forms the main structure of a butterfly valve, housing all other components. It is typically made from stainless steel, cast iron, or other durable materials to withstand pressure and environmental conditions. The body design can be lug type, wafer type, or flanged, depending on the installation requirement.

Disc or Butterfly Plate

The disc is the central component that rotates to allow or block flow. Its shape and material impact flow efficiency, pressure handling, and chemical compatibility. Discs are commonly made of stainless steel, ductile iron, or coated metals for enhanced corrosion resistance.

Stem or Shaft

The stem connects the actuator or handle to the disc, transmitting torque for rotation. It is precision-engineered to prevent leakage and ensure smooth operation. Materials used include stainless steel and high-strength alloys to handle mechanical stress.

Seat

The seat provides a sealing surface between the disc and the valve body, ensuring leak-proof operation. Seats can be soft (like EPDM, PTFE) or metallic, depending on temperature, pressure, and chemical compatibility. Proper seat selection is critical for valve performance and longevity.

Actuator or Handle

The actuator or handle facilitates manual or automated operation. Manual handles allow direct rotation of the disc, while gear operators, pneumatic, or electric actuators provide precise control for industrial automation systems.

Bearings and Bushings

Bearings and bushings support the stem and disc, reducing friction and wear. High-quality bearings ensure smooth operation, especially in high-cycle applications, and extend the service life of the valve.

Other Components

Additional parts include:

• Bolts and nuts: Secure the valve body and actuator assembly.
• Gaskets: Provide leak-proof connections between flanged surfaces.
• O-rings: Seal the stem and prevent fluid leakage.
• End connections: Include flanged, wafer, or lug types for pipeline integration.

Summary Table of Butterfly Valve Parts